Process for preparing varnish



C. T. BRAGG.-

PROCESS FOR PREPARING VARNISH.

APPLICATION FILED JAN.29. 1919.

1,332,749. Patented Apr. 20, 1920. fil /9:1 [479-2.

' AZ; ,3; 344 i 4% g INVENTOI? x T Jar 0%5/19 g g w m az UNITED STATES PATENT OFFICE.

CHARLES T. BRAGG, OF DETRQIT, MICHIGAN, ASSIGNOR TO MAX BAER AND ABE BAER,

OF NEW YORK, N. Y.

PROCESS FOR PREPARING VARNISH.

Specification of Letters Patent.

Patented Apr. 20, 1920.

Application filed January 29, 1919. Serial No. 273,816.

To all whom it may concern:

Be it known that I, CHARLES T. BRAGG, a citizen of the United States, and a resident of Detroit, Michigan, have invented certain new and useful Improvements in Processes for Preparing Varnish, of which the following is a specification.

The present invention relates to an improved process for preparing varnish, and includes in this definition the melting of resin or copal, or other ingredients of vartion is shown in the accompanying drawingsandthis will be hereinafter more fully described with reference thereto and the invention will be finally pointed out in the claims.

In the accompanying drawings:

Figure 1 is a vertical longitudinal sectional view of a furnace adapted to carry out my invention;

Fig. 2 is a vertical transverse sectional view thereof; I

Fig. 3 is a vertical longitudinal sectional view of a varnish making house containing a furnace of the type disclosed herein; and

Fig. 4 is a plan vicwthereof.

Similar reference characters indicate corresponding parts throughout the several figures of the drawings.

' The peculiarity of varnish making is such that the temperature, the atmospheric conditions and type of heat used in cooking or melting, control to a great extent, the product produced, and due to the uncertainty of these conditions, variations in the product are unavoidable with the methods and types of varnish cooking apparatus at present in use. Attempts have been made to cook varnish by super-heated steam in jacketed kettles with a view to eliminate fire danger but for the most part the well known method of cooking over a coke fire has prevailed, principally because the steam did not produce a type of heat suitable for varnish cooking and such steam apparatus did not permit of the convenient portage of the vessel which is necessary in cooling. The usual type of apparatus employing coke, or as sometimes is the case coal or gas, consists of a furnace having a fire set just below the floor level in which the coke, coal or gas is burning, and a tall and spacious chimney for the purpose of carrying off the fumes as well as the products of combustion, and a cylindrical copper kettle supported upon a truck by means of which the kettle may be moved over the fire and also drawn from the fire to a cooling room where it is thinned by the addition of turpentine or benzin.

Much danger of explosion and fire attended the use of the open coke fire as the oils and resins would ignite as they came in contact therewith either from boiling over or from back draft in the stack which would cause the fumes to be blown into contact with the fire. Usually these fires which were not of infrequent occurrence, would result in complete loss of the charge being cooked and often the destruction of the plant.

In order to obtain the best results in varnish cooking, a uniform temperature should be maintained during certain periods and this temperature should always be under control in order to prevent boiling over and over heating. This has, up to the present, been a theoretical condition only as the known apparatus and processes were not capable of fulfilling such requirements and even with the mostvskilled attendants there was always considerable variation in the temperature, and uncertainty in the product.

The action of the direct open fire on the vessel caused rapid deterioration of the vessel and also resulted in carbonization of certain organic "impurities in the resin, the resultant product being dark in color. This dark color is most pronounced in the poorer grades of resin and in order to eliminate it to some extent a much higher grade of resin had to be used so that light color varnishes are therefore relatively more expensive.

- the direct action of the flame upon the cop- 'per kettles would result in a chemical reaction between the metal of the kettle and the contents of the same which would tend to produce an inferior varnish.

According to the present invention an apparatus suitable for carrying out the same, comprises a pit or recess 10 provided in the floor 11, the pit being lined with re fractory fire brick or the like, and being preferably of trough shape, the longitudinal sides 10 and 10 being inclined to the elongated relatively narrow base. Above the pit 10 there is disposed a cover or plate 12 preferably of cast iron, having its upper surface flush with the floor 11 and reinforced at its under side by ribs 12- and extending upwardly from and surrounding the plate 12 there is provided a heat retaining Wall13, the front portion of which is in the form of a swinging door adapted to be swung open as shown in Fig. 4 to permit of the insertion or removal of the tank 14.- containing varnish making ingredients.

The heating element is of any type to produce a constant source of radiant heat energy, accurately controllableas to its in tensity, and to this end I provide in the present embodiment a resistance block 15 of carbonized graphite extending longitudinally of the pit. The block is (if such shape Y rier 33 as shown in that its surfaces radiate heat to the plate 12 as indicated by the arrows in Fig. 2, the plate conducting the heat to the tank 14:.

A suitable building for housing the apparatus comprises a tank room 21 containing the furnace and provided at its top with a vent 22, no stack being necessary as with old types of varnish plants, and a transformer room 23 into which extend the conduc'tors 19, 20 of the resistance block, and in which is'placed the transformer 24, the fuse board 25 and the switch 26, the handle 27 of which extends through an opening 28 into the tank room within easy reach of the attendant. I

The entrance door of the tank room extends to the ceiling, a track or I-beam'29 extending along the ceiling above the furnace and out of the tank room to a cooling room or out of doors, a block and tackle 31 being provided suspended from a carrier 30 slidable upon the-track for raising and lowering the tank which is provided with t'runnions 32 for this purpose. The tank may also be conveyed by means of a wheel car- Figu-2.

A removable cover 34 of asbestos or other suitable material is placed over the tank and rests upon the walls 13 being provided witha hole 35 which serves as a vent for the escapingfumes and for insertion of a stirring rod. The temperature within the pit is shown by a pyrometer 36 while that within the confined space surroundin the tank is shown by a thermometer 37. nother thermonieter 38 provided in.the cover 341 shows the temperature within the tank.

The process of cooking varnish according to the present invention consists in placing the tank containing the ingredients of the varnish in a heating furnace or oven in which there is no open fire and in which the tank and the .room in which the same is placed is free of any open fire or products of combustion, and heating the same by a radiant heat, the present disclosed apparatus having the plate 12 upon which the tank rests and upon which the heat rays are directed and then conducted to the tank. The intensity of the heat is accurately controllable at all times by the attendant-by merely manipulating the switch handle 27 so that the process of cooking may be carried out in a theoretically perfect manner depending upon the particular ingredients being used.

When separately melting copal or resin, previous to the addition of oil, it is necessary to remove the tank after melting in order to add the oil as is the custom with coke furnaces but as soon as the melting is completed, the current is turned off and the oil may be added without danger of igniting and at just the proper moment. The certainty with which the intensity of the heat may be controlled, enables the 'resin to be melted under uniform and predetermined conditions and with less dependence on the skill of the attendant. This is a very desirable feature, as carelessness, variations in temperature, over heating and other such contingencies render the product of inferior quality. Even with the more costly resins which under the best conditions of cooking rod'uce .a varnish of a pale .color, over-heating of an extra minute or two after the melting is completed, ma result in cansing resin to become dark. nasmuch as the heating may be immediately stopped when the proper melting point is reached, there is no danger of over heating and asthe re'sin may be cooked without the presence of an open fire, the inferior quality of resins which become dark even when not over heated, will retain their pale color.

Due to the accurate control and the constant heating effect provided by the present invention, the process lends itself particu larly well to those methods where melting boil over, are segregated from the heating element. This latter condition is reduced to a minimum as the attendant may always control the intensity of the heat and therefore reduce it before there is danger of the ingredients boiling over.

The type of heat with which the tank is protected from the direct effects of flame does not rapidly deteriorate the tank and eliminates the chemical reaction which occurs between the metal and the contents of the tank when there is a direct heating or surging flame against the same. The present type of heat may be described as uniform, gentle, but of the necessary intensity, and conducted free from flame or products of combustion.

With the use of the present process and apparatus, a prolonged gentle cooking of the oil and resin may be carried on pro ducing a better union of the ingredients, and a consequently better and more durable varnish than was possible with the old methods, the varnish thus produced being rather a compound than a mixture.

The present process furthermore permits of the. addition of such inflammable ingredients as benzin or turpentine without danger of the same igniting and this may be done when the ingredients in the tank are at such a temperature that the added ingredients will properly combine therewith to the end that a better final product will be produced. According to the old methods it was necessary that the ingredients in the tank be carried to a cooling room before addition of the turpentine and benzin and consequently the resins and other substances would cool below a temperature at which it the effects of heat constantl as to intensity, completely s iutting off said -was desirable to add the turpentine or which consists in placing the vessel containing the varnish ingredients within an inclosure, subjecting said inclosure to radiant heat from an electric heating element disposed within an inclosure exterior of the said first mentioned inclosure, the interior of said first mentioned inclosure and the approach thereto being at all times segregated from direct exposure to said heatin element.

2. In the. art of varnish making, that step which consists in subjecting the Varnish ingredients out of the presence of a flame to under control heat at the completion of said heating and removing said vessel after shutting off of said heat.

In testimony that. I claim the foregoing as my invention, I have signed my name hereunder.

0. T. BRAGG.

Witnesses:

F. E. PARKER, O. A. GUTTENBERG. 

